Schools play a key role in ensuring that children are being
immunized against diseases, but conflicting research is making enforcement
difficult.

Schools play a key role in ensuring that children are
being immunized against diseases, but conflicting research is making
enforcement difficult.

When whooping cough first turned up in Westchester County, N.Y., a
year ago, it wasn’t necessarily noteworthy. True, the contagious
bacterial infection was once a major cause of death among infants and
young children in the United States. But that was before widespread
immunization, and Westchester County typically sees only five or six
cases a year.

The 2003-04 school year was different for the wealthy New York City
suburb. In October, local newspapers were reporting confirmed cases of
whooping cough in two adults and 17 children in Westchester
communities. By April, five infants had been hospitalized, and the
outbreak had spread to nearly 100 people in the county, many of them
children who were classmates.

The Westchester County health commissioner, Dr. Joshua Lipsman, is
still counting cases. Most troubling, he says, is that "this outbreak
began with unvaccinated children who were old enough to be vaccinated."
Each year in the United States, 2.1 million children ages 19 months to
35 months are classified as "undervaccinated," lacking shots for
infectious diseases such as whooping cough, hepatitis, and polio.
Typically, studies show, such youngsters are members of racial or
ethnic minorities living in poverty in urban areas with mothers who
lack college degrees.

But the growing number of children who receive no vaccines at all
fit a different profile, says Philip J. Smith, a mathematical
statistician with the federal Centers for Disease Control and
Prevention’s National Immunization Program.

Recent research puts the number of unvaccinated youngsters in the
United States at roughly 17,000 a year, or 0.3 percent of children 19
to 35 months old. Those preschoolers tend to be white and male, to have
married mothers with college degrees, and to live in households with
annual incomes over $75,000, according to research led by Smith and
published this month in Pediatrics, the scientific journal of
the American Academy of Pediatrics.

That study of nearly 152,000 children also shows that the
unvaccinated tend to be children of parents who are worried about
potentially harmful side effects of immunizations, and who say that
their doctors have no sway over their decisions to forgo vaccines for
their children.

Perhaps most troubling of all from a public-health perspective are
recent data showing that families with unvaccinated children tend to
cluster in communities in certain parts of the country.

Westchester County, for example, was No. 6 on the list of counties
with the highest numbers of unvaccinated children in the country,
according to Smith’s analysis of national immunization data from
1995 to 2001. Los Angeles topped the list with 465 unvaccinated
children.

"What we’ve seen around the United States is that unvaccinated
children are very frequently at the bottom of outbreaks of
vaccine-preventable disease," Smith says. "With no vaccines, these
children are at risk for contracting pertussis, measles, and many other
preventable disease, and they can then spread these diseases to other
groups of children."

Driving the growing trend of vaccine avoidance is a seemingly
endless supply of conflicting information and research about
immunization safety.

Combination VaccinesA combination vaccine is more than one
vaccine contained in a single shot. Many doctors and parents prefer
that method because it allows a child to get several vaccines at
once with fewer injections. Several combination vaccines are
already in use, such as MMR (Measles, Mumps, Rubella), DTaP
(Diphtheria, Tetanus, Pertussis), and Hib/Hepatitis B (Haemophilus
Influenzae Type B/Hepatitis B).

SOURCE: Centers for Disease Control and
Prevention

Immunizations have reduced the incidence of disease by more than 95
percent for every pediatric vaccine recommended for routine use before
1990, according to the CDC.

As the number of immunizations for children has increased, however,
so have reports of vaccine side effects. That situation—combined
with the scant experience younger generations have with the diseases
controlled by vaccines—has led to an intense focus on the safety
of vaccines, health experts say.

"For older generations, who saw children die from these diseases
before there were vaccines, vaccination is a given," says Deborah A.
Gust, a behavioral scientist with the CDC’s National Immunization
Program. "But younger parents have had no experience with these
diseases. What they’re mostly hearing about is side effects from
the vaccines—and they have questions."

In an effort to answer those questions, the CDC and the National
Institute of Health’s Institute of Medicine sponsored a panel of
14 independent experts in the areas of medicine, public health, and
scientific research to study ongoing and emerging vaccine-safety
issues. The committee first met in January 2001 and, for the next three
years, explored some of the most controversial claims dogging this
country’s immunization program.

Do the influenza and hepatitis-B vaccines lead to neurological
disorders? Do multiple immunizations cause the immune system to
malfunction? Are some vaccines at the root of sudden infant death
syndrome? And do vaccines—particularly the shot for measles,
mumps, and rubella, or MMR—trigger autism?

In a series of eight reports, the panel did recommend some areas
that needed further research. But in no case did it find enough
evidence of risk to recommend changing the nation’s current
vaccine policies.

As for the MMR-autism debate, "that’s an easy one for me,"
says Dr. Marie C. McCormick, the committee’s chairwoman and a
professor of maternal and child medicine at Harvard University. "The
question has been out there for almost four years now, and 14
epidemiological studies have found no evidence of a causal
relationship."

Though some advocacy groups and scientists disagree with that and
other findings reached by the committee, the panel’s work leads
to the conclusion that not having a child vaccinated is more dangerous
than submitting him or her to the recommended regimen of shots.

Parents who opt out of immunization for safety reasons are
"responding to a hypothetical risk, compared to the very real risk of
some very bad diseases," McCormick says.

But conflicting evidence continues to emerge.

Barely a month after the Institute of Medicine panel released its
report concluding that "the evidence favors rejection of a causal
relationship between thimerosal-containing vaccines and autism," a new
study of mice that suggests otherwise was released by Columbia
University.

The central finding of the research—that the mercury
preservative thimerosal can cause autism-like behavior in mice with a
specific genetic susceptibility—made headlines and reinvigorated
the arguments of parent activists.

Despite the controversy, many people appear to accept the health
community’s assurances that vaccines are safe and beneficial.

By and large, the credit for ensuring that most children receive the
recommended vaccines before they enter school goes to the states. No
federal law requires that children be vaccinated, but all 50 states
mandate that children be immunized against a range of infectious
diseases such as measles, hepatitis B, pertussis, and tetanus before
they enter school.

Experts say the laws are not airtight, though.

To begin with, all states permit medical exemptions from vaccination
for people with immune-system problems, allergies to vaccine
ingredients, moderate or severe illness, or other health problems,
according to a paper written by Daniel A. Salmon, an associate director
of the Vaccine Safety Institute at Johns Hopkins University in
Baltimore.

In addition, 48 states allow children to opt out of compulsory
vaccination for religious reasons, and 19 allow philosophical or
personal exemptions in an effort to accommodate a minority that
researchers say represents less than 1 percent of the population.

The CDC’s Smith writes in his study of unvaccinated children
that "in many states, it is easier to claim a religious or
philosophical exemption than to adhere to mandated immunization
requirements."

In some cases, it’s as simple as checking a box when a child
enters school, Smith says. And his study notes that states that allow
philosophical exemptions to their immunization laws have had
significantly higher estimated rates of unvaccinated children than
states that do not allow exemptions.

There are consequences for states allowing exemptions, according to
researchers.

What if a Child Misses a Shot?For most vaccines, it is never too late
to catch up on missed shots. Children who missed their first shots
at 2 months of age can start later. Children who have gotten some
of their shots but then have fallen behind schedule can catch up
without having to start over. For school-age children who were not
immunized when they were infants, or who have gotten behind
schedule, a doctor or the local health department can provide
information on how those children can be updated on their
immunizations.

SOURCE: Centers for Disease Control and
Prevention

In a study published in 1999, Salmon of Johns Hopkins found that, on
average, people who claimed exemptions were 35 times more likely than
vaccinated individuals to contract measles.

And the tendency of groups that opt out of immunization to settle in
certain geographic regions doesn’t raise only those groups’
risk of contracting vaccine-preventable disease, he concludes. It also
threatens the health of surrounding communities, placing at risk
children who are too young to be vaccinated, people avoiding vaccines
for medical reasons, and those for whom vaccines simply didn’t
"take."

The largest numbers of unvaccinated children are clustered in
counties in the states of California, Colorado, Illinois, Michigan, New
York, Oklahoma, Pennsylvania, Texas, Utah, and Washington.

As Harvard’s Dr. McCormick puts it, "If you live in one of
those states, near one of those communities, there’s no question
you’re at greater risk.

"Look at Boulder, Colorado," she says, referring to a county with
one of the highest rates of unvaccinated children in the country. "The
people living in the counties around Boulder know where their pertussis
comes from every year."

Just over 60 percent of all children ages 19 months to 35 months in
the United States are fully vaccinated, according to federal data. But
that success rate may not be stable, according to research led by the
CDC’s Gust and published in Pediatrics this month.

From a 2001 survey of 2,315 households that had participated in the
federal government’s National Immunization Survey, Gust concludes
that vaccine-safety concerns are contributing "substantially" to the
country’s problem of underimmunization.

Just over 60 percent of all children ages 19 months to
35 months in the United States are fully vaccinated.

What’s worse, she writes, is the finding that even parents who
had their children fully immunized were worried about the potential
side effects of those vaccines, "suggesting a risk to the currently
high vaccination levels." "We have to stop expecting people to do this
because we say so," Gust said in a recent interview. "We’re
living in an era where we can’t rely on disease to prove to
people that immunization is a good idea. We need to do a better job
explaining to parents why this is a good idea."

Getting school health workers on board is critical to that effort,
health professionals and researchers say.

A study in the June issue of Pediatrics—based on survey
results from 594 schools in Colorado, Massachusetts, Missouri, and
Washington state—found that trained nurses were more likely than
other school personnel to be supportive of immunization, and that
schools with trained nurses were the least likely to have students who
claimed vaccine exemptions.

But the researchers, led by Salmon of Johns Hopkins University, also
found that too many survey respondents who identified themselves as
working with parents on immunization for their schools were misinformed
about the value of vaccines. "Many school personnel seem to be unaware
of the seriousness of some vaccine-preventable diseases and that
unimmunized children are highly susceptible to diseases," the
researchers conclude. "These misperceptions were associated with an
increased likelihood of a child having an exemption."

Meanwhile, in Westchester County, Dr. Lipsman says he’s
counting on schools to help prevent future outbreaks of dangerous
disease. As whooping cough spread through the county this past school
year, the health commissioner urged school health officials to review
students’ immunization records carefully and pressure parents
whose children lacked mandated vaccines to get them.

"The state does audits, but it doesn’t look at every
child’s record," Lipsman says. "The rubber really meets the road
at the schoolhouse."

Coverage of research is underwritten in part by a grant from the
Spencer Foundation.

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